over two crown and under two wall diamond knotsThe diamond knot is an attractive stopper knot but can loosen when handled, especially when nylon or other synthetic material is used.
Using the over two crown knot or under two wall knot increases the number of cords that each strand passes under.
That increase in crossings makes the knot much more secure than the regular crown knot.
Over two crown diaamond knot and regular diamond
over two crown diamond tutorialUnder two wall diamond and regular diamond
under two wall diamond tutorialIf you combine the over two crown and under two wall knots you will get a
supersecure knot, not much bulkier than the regular diamond